1. Field of the Invention
This invention is related generally to medical devices for preventing and treating cranial deformities in infants. In particular, the invention is related to a protective appliance or cranial orthosis in the form of a shell, helmet or headband that fits around a baby's head, and the use of the appliance to prevent positional plagiocephaly by redirecting the compressive forces that would otherwise be imposed on soft, compliant areas of the developing cranium by the head weight of an infant lying on a sleep surface in the supine position.
2. Description of the Related Art
Cranial asymmetry (plagiocephaly) and deformations may occur from various congenital causes including premature closure of the cranial vault and/or skull base sutures (craniosynostosis), syndromal craniofacial dysostosis, intracranial volume disorders such as hydrocephalus, microcephaly or tumor, metabolic bone disorders such as rickets and birth trauma such as depressed skull fractures. Cranial deformity (cranial molding) may also be acquired in an infant as the result of compressive forces imposed by the infant's head weight on the soft, compliant occipital areas while the infant is lying on a sleep surface in the supine position. This condition typically occurs during the first twelve months of development before the cranium is fully expanded and the brain is fully developed.
Generally, plagiocephaly is characterized by unilateral occipital flattening with contralateral occipital bulging, producing a flat spot at the back of the infant's head. The flat spot and bulging make the baby's head appear to be square or box-shaped in profile. As the deformation becomes more severe there is ipsilateral forehead protrusion, contralateral forehead flattening and endocranial skull base rotation with anterior displacement of the ipsilateral ear. If not prevented or corrected during the first twelve months of development, the deformity may become permanent.
The number of infants diagnosed with plagiocephaly increased substantially shortly after the onset of the “Back-to-Sleep” campaign by the American Academy of Pediatrics (AAP) in 1992. In that campaign, the AAP recommended that infants be placed in the supine (lying on the back, face up) sleeping position in an effort to decrease the incidence of sudden infant death syndrome (SIDS), a leading cause of early infantile deaths in the United States at that time. That campaign resulted in a substantial decrease in the incidence of SIDS. However, the incidence of plagiocephaly was observed to increase significantly over the same period. This correlation suggests that positional treatment for SIDS was the probable cause of the increased incidence of infant plagiocephaly. The consensus of craniofacial practitioners is that plagiocephaly may be acquired as a result of cranial postural molding that occurs during SIDS positional treatment. That condition is now referred to as positional plagiocephaly or acquired plagiocephaly, to distinguish it from congenital plagiocephaly.
Postural molding of the newborn's skull is common, and this presents clinically as occipital flattening, referred to as acquired plagiocephaly (or brachycephaly). Although some mild asymmetrical molding of the infant's cranial vault is likely common as a result of back sleeping, some babies develop severe cranial deformities that should be corrected. These deformities are typically characterized by flattening of only one occiput. The ipsilateral ear is displaced forward. There is compensatory bulging of the contralateral occipital area, the ipsilateral high parietal vertex, the ipsilateral temporal area, and occasionally the ipsilateral forehead. Bioccipital flattening is less commonly seen. These are acquired cranial deformities, and should be distinguished from congenital cranial deformities that result from the premature closure of a cranial surture (i.e., craniosynostosis). The latter condition frequently requires craniofacial surgery in order to correct the cranial deformity.
Positional plagiocephaly (postural molding of the cranium) may be prevented by periodically repositioning (turning over) the infant's head during sleeping. The “turn-over” repositioning treatment is not difficult to accomplish. However, to be effective this technique requires careful monitoring of the baby, diligence and the close attention of parents during sleeping hours. Although this seems simple in theory, in practice it is most difficult to accomplish consistently over the treatment term, which may extend up to 12 months, because of obligations parents may have to care for other children and attend to other matters, while at the same time trying to obtain the sleep and rest needed to carry on with work and other activities.
Infants more than three months of age and those who have not responded to repositioning may be treated with a custom-made cranial torque helmet. The torque helmet, which is precisely manufactured from an exact mold of the infant's head, continuously applies pressure or torque to the cranium to correct asymmetric deformities. The corrective forces have proven effective in some cases to restore cranial symmetry by helping the growing brain to reshape the cranium while it is still soft and compliant. The torque helmet is worn continuously, day and night, and is removed only for bathing until the child is twelve months of age or older. After twelve months of age or if the deformity is severe, torque helmets are of limited value and surgical cranial re-contouring may be required.
Custom-fitted, conventional torque devices have treated these acquired cranial deformities with varying degrees of success. The success has depended in large part on the age of the patient at the time torque treatment is begun. Clinical improvement occurs most rapidly in young infants (3 to 5 months of age). Treatment with these torque devices typically requires more time in older infants. As a child's age approaches 12 months, torque treatment becomes less effective. Many craniofacial physicians feel that little is gained with a cranial orthotic device after 12 months of age. Moreover, the acquired distortion of the base of the skull, as evidenced by the forward displacement of the ear on the side of the occipital flattening, does not generally improve with torque treatment devices. The petrous pyramids of the base of the skull tend to rigidly reinforce the skull base and resist external torsion/correction of the acquired cranial deformity .
Not infrequently, infants undergoing cranial torque treatment require re-fitting and replacement of the cranial orthosis to accommodate head growth as the child develops and the cranial deformity changes (responds). Because each orthosis is custom manufactured from an exact mold of the child's head, and because each device requires follow-up and modification as the child grows and the deformity responds, these devices are expensive and beyond the reach of many families, in particular those without effective insurance coverage. Some commercial insurance companies do not reimburse for the manufacture and use of such cranial orthotic devices, because the cranial deformities are acquired and are not the result of craniosynostosis (suture fusion).
It is therefore evident that a protective appliance is very much needed for all newborns and infants, in order to prevent the development of occipital flattening as a result of postural molding. Moreover, such a protective appliance should be universally available to all infants without requiring costly procedures to custom-fit the device to the individual infant. Rather, the protective appliance should be available on an “off-the-shelf” basis, using simple measurements such as head circumference to determine appropriate sizing. Finally, the protective appliance should be safe, simple to understand and use, relatively inexpensive and easily within the means of all families, even those without insurance coverage, so that preventive care and treatment can begin immediately after birth and continue at home without professional assistance other than the usual well baby check-ups.